Lithium secondary batteries have high voltage and high capacity, and thus have been widely used as power supplies of mobile phones, digital cameras, camcorders, notebook computers, electric vehicles and the like. A lithium secondary battery generally distributed contains an electrolyte which is a liquid electrolyte containing an electrolyte salt dissolved in a non-aqueous solvent. As non-aqueous solvents include a number of flammable solvents, there is a need for assuring safety.
For the purpose of assuring safety, an all-solid-state secondary battery has been proposed that contains a so-called solid electrolyte formed from a solid material, Li2S—P2S5, devoid of a non-aqueous solvent (Non-Patent Document 1).